Fuel injection nozzle



March 6, 1962 CLEMINSHAW ETAL mums FUEL INJECTION NOZZLE Filed May 27,1959 INVENTOR. WILLIAM T CLEMINSHAW WILLIAM J. GILLET OMW, 77 D ifiTORNEYS iinited ttes atc if 3,Z4,fid5 Patented Mar. 6, 1952 3,024,045FUEL INJECTION NOZZLE William T. Cleminshaw, Cleveland, and William 5.(lil- The present invention relates generally as indicated to a fuelinjection nozzle and more particularly to improvements in a fuelinjection nozzle for gas turbines and the like.

At the present time so-called dual orifice nozzles are in extensive useand essentially such nozzles are formed with a primary fuel supplypassage which leads to the primary discharge orifice of the nozzle byway of swirl slots or the like, which impart to the fuel a whirlingmotion so that upon leaving the orifice it is broken up into finedroplets and spread out in conic-a1 spray pattern form. Such nozzle isalso provided with a secondary fuel supply passage through which fuel issupplied through a secondary discharge orifice (usually annular)disposed concentrically around the aforesaid prim-ary orifice, andagain, swirl slots are provided in the secondary fuel passage to impartwhirling motion to the fuel for discharge in fine droplet and conicalspray pattern form. Such nozzle usually has associated therewith a flowdivider so that at low fuel flows, the fuel is discharged only throughthe primary orifice to achieve efiicien-t atomization while for greaterfuel flows, the fuel is discharged from both the primary and secondaryorifices, proper atomization being achieved by reason of the greatervelocities through the nozzle.

Such dual orifice nozzles include a holder and a nozzle body threadedlyconnected thereto, the nozzle body being a member which defines theouter wall of the secondary fuel passage, secondary swirl chamber, andsecondary orifice. Such threaded joint is usually sealed by a suitablepacking ring interposed between radially opposed shoulders of the holderand nozzle body. However, it has been found that under varyingconditions of operation of the gas turbine with which the nozzle isused, such packing ring is not reliable as a leakproof seal and will, intime, evidently due to alternate expansion and contraction of the nozzleparts, lose its effectiveness in preventing leakage of fuel through thethreaded join-t between the holder and nozzle body. Heretofore it haseen impractical to braze or weld together these threadedly engagednozzle par-ts, since, although the problem of fuel leakage may be solvedthereby, it would then be substantially impossible to disassemble theholder and nozzle body for cleaning, adjustment, or replacement ofinternal parts thereof because the brazing or welding metal wouldinevitably find its way to the threads. Thus, if such nozzles of weldedor brazed construction would become wholly or partly inoperative due toforeign matter or wearing of parts therewithin, it would be necessary todiscard the complete nozzles and replace them with new ones.

Accordingly, with the foregoing in mind, it is one principal object ofthis invention to provide a fuel injec-.

tion nozzle in which the holder and nozzle body are threadedly engagedand are bonded together, that is welded or brazed, in such a manner thatthe bonding agent is isolated from the threads whereby it is a simplematter to machine away the bonding agent to .permit unscrewing of thenozzle body to get access to the interior parts of the nozzle forcleaning, adjustment, or replacement.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail a certain illustrativeembodiment of the invention, this being indicative, however, of but oneof the various ways in which the principle of the invention may beemployed.

In said annexed drawing:

FIG. 1 is a fragmentary cross-section view diametrically through apreferred form of fuel injection nozzle embodying the present invention;and

FIG. 2 is a fragmentary and much enlarged radial cross-section viewshowing how the threaded-on nozzle body is rendered readily removabledespite the fact that it is bonded by welding or brazing to the nozzlebody to provide the required foolproof fluid-tight connection betweenthe holder and nozzle body.

Referring now in detail to the drawing, the holder 1 is herein shown asbeing in the form of an elbow of which one leg 2 is externally threadedat 3 up to an annular shoulder 4 which preferably lies in a planeperpendicular to the axis of such threads 3, said leg 2 being formedwith a secondary fuel flow passage 5. intersecting the passage 5 is thesecondary fuel passage 6 formed in the other leg 7 of the holder 1 andconnected to said passage 6 as by welding is the end portion of thesecondary fuel supply conduit 8 which has its other end (not shown)connected in well-known manner to a suitable fiow divider or the like,which is effective to supply fuel into said secondary conduit 8 inaccordance with the demand for fuel required by the gas turbine or thelike.

Located concentrically within the leg 2 of the holder 1 is a tubularinsert 9 which has its inner end fitted into and brazed in an opening 10which communicates with the primary fuel passage ll formed in the leg 7of the holder 1. The outer end portion of said tubular insert 9 isformed with circumferentially spaced radially extending legs 12 whichalso are secured by brazing or like expedient, in fixed position at theend of the secondary fuel passage 5.

Leading to the primary passage 11 and secured thereto as by welding, isthe end portion of the primary fuel supply conduit 14 which has itsother end (not shown) connected with a fuel supply source, usually aport which has constant communication with the inlet of the aforesaidflow divider. Surrounding the primary and secondary fuel supply lines 8and 14 is a heat shielding tube 15 which is telescoped over the leg 7 ofthe nozzle body 1 and over a corresponding leg or boss (not shown)formed on the fuel flow divider valve.

Coming back now to the tubular insert 9, which is bored to provide theprimary fuel passage 15, its outer end portion is internally threadedfor screwing thereinto the externally threaded connector 17 which thusprovides exposed axially extending external threads on which the primarynozzle 18 is screwed with its inner end in firm abuttin engagement withthe end of the tubular insert 9.

Said primary nozzle 18 has an enlarged head which is formed with aplurality of helic-ally disposed grooves or swirl slots 19 on itsperiphery, and with a frustoconical end portion which terminates in anaxially extending lip 20 which, together with the frusto-conical wall 21and central opening 23 in the nozzle body 24, define a swirl chamber andthe secondary annular discharge orifice 25. Thus, as shown, when fuel issupplied through the secondary fuel line 8, the fuel flows through theannular space between the passage .5 and the tubular insert 9, betweenthe legs 12 of the tubular insert 9, and thence through the swirl slots19 whereby the fuel has imparted thereto a progressively increasingswirl velocity as it approaches the secondary orifice 25 and, of course,

the swirling fuel under pressure emerges from the secondary orifice 25in fine droplet and conical spray pattern form.

Said primary nozzle 18 is also formed with the primary orifice 26 and,in addition, has the swirl producing primary plug 27 disposed thereinwhich, as shown, has a support spider or guide at one end and a swirlslot head at the other end disposed to impart swirling velocity to thefuel which is supplied from the primary fuel supply line 14 and flowsthrough the passage 16 of the tubular insert 9, through the connector17, and through the openings in the spider and the swirl slots in thehead of the primary plug 27 for discharge in fine droplet and conicalspray form from the primary orifice 26.

The nozzle body 24 previously referred to is formed with internalthreads which have threaded engagement with the threads 3 of the leg 2of the holder 1 and said nozzle body 24 is adapted to be screwed ontightly until the internal shoulder 28 therein engages the annular endface of the holder 1.

Spot welded, or otherwise secured, on the nozzle body 24 is a shroud 29which forms an annular air space around the discharge end portion of thenozzle body 24.

As shown in FIG. 1, the internally threaded end of the nozzle body 24terminates in an annular end surface 30 which is axially spaced from andparallel to the shoulder 4 of the holder 1. Positioned between theannular faces 4 and 30 and surrounding the threads 3 of the holder 1 isa refractory ring 31 made, for example, of carbon or like material,which is capable of withstanding the high temperatures to which theholder 1 and nozzle body 24 are subjected when the welding operation isperformed. It has been found that the axial length of the refractoryring 31 should be slightly less (.010" to .020", for example) than theaxial distance between the faces 4 and 30 so that no stress is imposedon said ring 31 when the nozzle body 24 is screwed onto the holder 1. Asa matter of fact, it has been found that an axial clearance such asindicated above between the opposite ends of the refractory ring 31 andthe surfaces 4 and 30 is not at all objectionable since the weld metal32 is effectively prevented from flowing inward to the interengagedthreads of the nozzle body 24 and the holder 1.

In FIG. 1 is shown the assembled condition of the present fuel injectionnozzle with a ring 32 of weld metal integrally joining the holder 1 andnozzle body 24 so as to form a safe fluid-tight joint which will notonly prevent leakage of fuel but also loosening of the nozzle body 24due to vibration.

However, despite the fact that the nozzle body 24 and holder 1 are thusinseparably secured together in leakproof manner and against looseningdue to vibration, yet, if one so desires, the nozzle body 24 may easilybe removed from the holder 1 for cleaning or servicing of the interiorof the nozzle and then may be reassembled and rewelded to the holder 1.

Such disassembly is preferably done with a cut-off tool T or the likewhich is effective to cut away the welded section 32 to a Width which ispreferably at least equal to the axial length of the refractory ring 31,whereby, when the metal 32 is cut away down to the outside diameter ofthe ring 31 as shown in FIG. 2, it is a simple matter to unscrew thenozzle body 24 from the holder 1 to perform the necessary cleaning orother servicing operations. Then, after the servicing operation has beencompleted the nozzle body 24 is rescrewed onto the holder 1 and reweldedas in FIG. 1, to form an inseparable unitary assembly having afluid-tight threaded joint.

It is to be understood, of course, that a narrower tool T, even ahacksaw or the like, may be employed just so the tool penetrates thewelded section 32 down to the outside diameter of the refractory ring31, in which case the nozzle body 24 may be unscrewed from the holder 1despite the fact that the ring 31 then will be disposed in a counterboreconstituted by the weld metal 32. It has been found that a preferredrefractory material for the ring 31 is carbon since it appears not to bewetted by the fused steel alloy weld metal 32 whereby it serves as aneffective barrier against capillary flow of the fused metal into thethreads. Of course, other refractory materials may be employed.

It is apparent that the joint in accordance with the present inventionmay be applied to articles other than nozzles. Thus, it may be appliedto any members which have interlocking, overlapping, or adjacentsurfaces in the vicinity of the welding or brazing location and whichare to be protected or isolated so that the bonding material will bekept away therefrom.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equivalent ofsuch, be employed.

We therefore particularly point out and distinctly claim as ourinvention:

1. A leak-proof, welded, and threaded joint for a holder and nozzle bodyof a fuel injection nozzle or the like comprising a holder and a bodyformed with interengaged threads and defining an externally openperipheral groove adjacent the interengaged threads constituted byintegral axially spaced annular shoulders of said holder and bodyrespectively; a ring of refractory material in such groove having anoutside diameter less than the outside diameters of said shoulders; anda ring of Weld metal within said groove surrounding said refractory ringand bridging the gap between said shoulders thus to secure said holderand body together in leak-proof manner and against inad vertentloosening, said refractory ring constituting a barrier against flow ofweld metal into the interengaged threads whereby said holder and bodymay be unscrewed upon cutting away of weld metal to the outside diameterof said refractory ring but without cutting away of any of theinterengaged threads of said holder and body.

2. The joint of claim 1 wherein said holder and body are further formedwith abutting shoulders that determine the minimum axial length of thespace between said annular shoulders and that predetermine the relativeaxial positions of said holder and body irrespective of the number oftimes that the joint is disassembled and reassembled.

3. The joint of claim 2 wherein said refractory ring is of axial lengthshorter than the axial length of the space between said annularshoulders to preclude axial clamping stresses being imposed thereonwhile yet being effective to preclude flow of Weld metal between theends of said refractory ring and the respective annular shoulders.

4. The joint of claim 1 wherein said refractory ring is made of carbon.

5. The joint of claim 1 wherein said refractory ring is made of amaterial that is not wetted by the weld metal.

References Cited in the file of this patent UNITED STATES PATENTS Re.22,725 Von Ahrens Feb. 19, 1946 1,912,993 Murray June 6, 1933 1,931,311Young Oct. 17, 1933 2,234,957 Boynton Mar. 18, 1941 2,289,271 Kane et alJuly 7, 1942 2,451,587 Taylor Oct. 19, 1948 2,623,148 Ronay Dec. 23,1952 2,701,164 Purchas et a1 Feb. 1, 1955 2,762,904 Thomas Sept. 11,1956 2,764,426 Von Ahrens Sept. 25, 1956 2,792,241 Bondley et al May 14,1957

